Analog Devices VISUALDSP++ 3.5 Manual page 423

Various forms of the FFT function are provided by the library correspond-
ing to radix-2, radix-4, and two-dimensional FFTs. The number of points
is provided as an argument. The twiddle table for the FFT functions is
supplied as a separate argument and is normally calculated once during
program initialization.
Library functions are provided to initialize a twiddle table. A table can
accommodate several FFTs of different sizes by allocating the table at
maximum size, and then using the stride argument of the FFT function to
specify the step size through the table. If the stride argument is set to 1,
the FFT function will use all the table; if the FFT uses only half the num-
ber of points of the largest, the stride should be 2.
The functions defined in the
and Table 4-3
erence" on page
Table 4-2. Filter Library
Description
Finite Impulse
Response Filter
Infinite Impulse
Response Filter
FIR Decimation
Filter
FIR Interpolation
Filter
Complex Finite Impulse
Response Filter
VisualDSP++ 3.5 C/C++ Compiler and Library Manual
for ADSP-219x DSPs
filter.h
and are described in detail in
4-22.
Prototype
void fir_fr16
(const fract16 x[], fract16 y[],
int n, fir_state_fr16 *s);
void iir_fr16
(const fract16 x[], fract16 y[],
int n, iir_state_fr16 *s);
void fir_decima_fr16
(const fract16 x[], fract16 y[],
int n, fir_state_fr16 *s);
void fir_interp_fr16
(const fract16 x[], fract16 y[],
int n, fir_state_fr16 *s);
void cfir_fr16
(const complex_fract16 x[], complex_fract16 y[],
int n, cfir_state_fr16 *s);
DSP Run-Time Library
header file are listed in
"DSP Run-Time Library Ref-
Table 4-2
4-7